For example, when simultaneously polishing both surfaces of a semiconductor wafer, a carrier is utilized to hold the semiconductor wafer. This carrier is formed to have a thickness smaller than that of the semiconductor wafer and includes a holding hole that is utilized to hold the wafer at a predetermined position between an upper turn table and a lower turn table of a double-side polishing apparatus. The semiconductor wafer is inserted into and held in this holding hole, upper and lower surfaces of the semiconductor wafer are sandwiched between respective polishing instruments such as polishing pads provided on opposed surfaces of the upper turn table and the lower turn table, and polishing is carried out while supplying a polishing agent to surfaces to be polished.
Here, as the carrier utilized for double-side polishing in such a semiconductor wafer polishing process, a metal carrier is a mainstream.
Therefore, a resin insert is disposed along an inner peripheral portion of the holding hole to protect a wafer peripheral portion against damages caused by the metal carrier. In conventional examples, to prevent this resin insert from coming off during processing of the semiconductor wafer or conveyance when disposing it, an outer peripheral portion of the resin insert may be formed into a wedge shape and fitted into a carrier base to be further fixed by an adhesive in some cases (see JP-A 2000-24912 (KOKAI)).
Although this wedge shape is hollowed out from a plate material by laser beam machining, expansion or constriction occurs due to heat so that fitting may be tight when disposing the resin insert to the carrier base, whereby a wedge shape of the carrier base portion may be deformed in some cases.
To eliminate such deformation when disposing the resin insert, a process such as lapping for the carrier must be carried out after disposing the resin insert, and the lapping process cannot be performed when the carrier to be used is a coated carrier.
There is a problem that, when the carrier deformed by disposing the resin insert is utilized to polish the semiconductor wafer, a shape of the polished wafer is degraded.
Further, although a method of performing start-up polishing for the carrier in place of the lapping process can be considered, a longer time is required as compared with the lapping process and productivity is degraded in case of polishing, and accurately eliminating the deformation is difficult.